A distribution list is a list of members to whom an electronic mail message (EMM) delivered to the distribution list is passed on to. A distribution list allows a user to efficiently send an EMM to a list of addresses. An EMM may include, for example, an email, an instant message (IM), a short message service (SMS) message, multimedia content, hyperlinks to remote content, a meeting request, a task, or an appointment. In operation, the user prepares a single EMM, addresses it to the distribution list, and sends it. When the EMM is delivered to the distribution list, the EMM is forwarded to the addresses in the distribution list. The owners corresponding to the addresses in a distribution list typically share a common trait such as a political interest, a common business purpose, or a common set of friends. In a business setting, distribution lists are typically created for an entire company, each department of the company, each project group, and joint development projects including employees inside of the company and partners outside of the company.
Distribution lists are categorized as external or internal based on whether the addresses in the list are inside or outside of an enterprise associated with the list. An enterprise may be any computer networking structure such as a domain, collection of domains, or other organization. An example of an enterprise is the computer network of a company. Internal addresses are addresses inside of the enterprise associated with the distribution list, and external addresses are addresses outside of the enterprise associated with the distribution list. An internal distribution list has only internal addresses. An external list has at least one external address and may include any number of internal and external addresses. Some embodiments of an enterprise may store an authoritative list of domains in the enterprise and/or a global address list (GAL). To determine whether an address is internal or external to the enterprise, the enterprise may compare the address to the authoritative list of domains and/or the GAL. For example, the domain of an internal address would be found in the authoritative list of domains, and the complete address would be found in the GAL.
Distribution lists are also categorized as open or closed based on the availability of the distribution list to senders outside of an enterprise (i.e., owners of addresses external to the enterprise) associated with the distribution list. An open distribution list is available to senders outside of the enterprise (e.g., addresses outside of the company can send EMM to the distribution list). A closed distribution list is a distribution list that is denied to senders outside of the enterprise (e.g., addresses outside of the company cannot send EMM to the distribution list). In existing EMM systems, internal distribution lists are typically closed, and external distribution lists are typically open.
Open distribution lists can be used to distribute unwanted EMM (i.e., spam) because anyone on the Internet can send EMM to the list. In existing EMM systems, some external distribution lists are closed to reduce spamming, but this means that owners of external addresses on the distribution list cannot send EMM to the distribution list.
Some existing EMM systems use access control lists to limit access to distribution lists. An access control list is a list associated with a file, such as a distribution list, that contains information about which users or groups have permission to access or modify the file. Access control lists are generated and modified by system administrators to control user access to network resources, such as servers, directories, and files. Users other than administrators do not typically have permission to modify access control lists and even if they did have such permission, most users are not able to manipulate an access control list to achieve the desired results (e.g., changing which owners of addresses in a distribution list are allowed to send EMM to the distribution list or modify the access control list).